Transmitter optical subassemblies (TOSA's) may be assembled using a modular design. In one such approach, three primary subassemblies are employed: a port assembly, a nose assembly and an adapter assembly. The port assembly includes a laser diode device and supporting optics. The nose assembly includes mechanical elements for connecting with an optical fiber. The adapter assembly is used to attach the TOSA to a higher level assembly, such as an optical transceiver or transponder. TOSA's are primarily used in electro-optical converter devices for data communications and telecommunication applications.
The nose assembly is typically connected to the port assembly and the adapter assembly, so that the TOSA is secured in place and can receive the connector of an optical fiber. The alignment between the port assembly and the nose assembly must be precise so that light generated by the laser diode is efficiently coupled into an optical fiber connected to the TOSA. This is typically done by connecting an optical fiber to a nose assembly, positioning the nose assembly to the port assembly to maximize the amount of light coupled into the optical fiber, and then permanently affixing the port and nose assemblies together (e.g. welding, adhesives, solders, fasteners, etc.).
One problem with present TOSA manufacturing is that there are many different mechanical connector standard interfaces for optical fiber connectors (e.g. SC, ST, LC, FC, etc). Each such connector standard requires a different mechanical design of the nose assembly (e.g. different size/shape receptacles for receiving different sized/shaped ferrule connectors). Since port assemblies are also typically designed specially for the nose assembly to which it will attach, different port assembly designs are also necessary for the various connector standards. Thus, any given TOSA design is compatible with only one of the connector standards. In order to manufacture TOSA's compatible with the various connector standards, a unique TOSA design (having unique port, nose and adapter assembly designs compatible with one of the connector standards) must be separately made and stocked for each connector standard, which adds to manufacturing and inventory costs because each design version of the TOSA subassemblies must be designed, fabricated and stocked.